Effect of Ginseng Saponins on β-Amyloid-Suppressed Acetylcholine Release from Rat Hippocampal Slices

Abstract

In view of the facts that ginseng has been shown to improve age-related memory deficits and β-amyloid-related peptides have been suggested to play a significant role in memory degeneration in the elderly, the present study was carried out to examine the effect of various ginsenosides on β-amyloid peptides-modulated acetylcholine (ACh) release, a key neurotransmitter in memory processing, from the hippocampal slices. Addition of β-amyloid fragment_{25 - 35} (0.01 - 1 μM) in the superfusion medium suppressed the K⁺-evoked [³ H]-ACh release from the rat hippocampal slices in a concentration-related manner and about 40 % reduction in ACh outflow was observed when incubating with the highest concentration of an amyloid fragment (1 μM). Inclusion of the ginsenoside components Rb₁ (0.1 μM), but not Rg₁, caused a rightward shift of the concentration-response curve of β-amyloid. The reversal of the β-amyloid-inhibited ACh release by Rb₁ was not blocked by tetrodotoxin (1 μM) indicating that an interaction occurs at the cholinergic synapse. These results suggest that Rb₁ may elicit its anti-amnesic effect by minimizing the inhibitory effect of β-amyloid peptides.

Key words

Panax quinquefolius L. - Araliaceae - ginsenosides - β-amyloid - acetylcholine release - hippocampus

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